Update activation in lib/script.coffee

Listens for the <kbd>escape</kbd> key and closes the options and script views. This seems to be a standard way to close extra views in Atom. I really prefer this over the <kd>ctrl-w</kbd> and actual close button (for the options view). I figured this out by looking at the find/replace package source once I realized customizing a keymapping for <kbd>escape</kbd> to `script:close-options`/`script:close-options` could block other `escape` functions.